The listed items are constants day to day, particularly the fuel pressure since it is regulated. I am looking for a parameter to tune fuel economy, not the fuel economy itself. It seems the fuel economy is directly proportional, but not equal to, the injector pulse length times the number of injector pulses divided by the distance driven. If true, then if this parameter is optimized, the map will represent the best fuel economy. Is this correct and can I log the pulse length and number of pulses in real time?

You can't actually tune based on injector pulse and hope it magically works out. You have to watch a wideband at which point watching the injector pulse wouldn't do you any good. Just tune with the wideband for fuel efficiency or economy, whichever you're hoping to achieve.